[tex]\bf \textit{arc's length}\\\\ s=r\theta ~~ \begin{cases} r=radius\\ \theta =angle~in\\ \qquad radians\\[-0.5em] \hrulefill\\ s=14\pi \\ r=12 \end{cases}\implies 14\pi =12\theta \implies \cfrac{14\pi }{12}=\theta \\\\\\ \stackrel{\textit{radians}}{\cfrac{7\pi }{6}}=\theta ~\hspace{10em}\stackrel{\textit{in degrees}}{210^o}[/tex]